Section 1613 — California Building Code (Title 24, Part 2)

1613.1 Scope.¶

Every structure, and portion thereof, including nonstructural components that are permanently attached to structures and their supports and attachments, shall be designed and constructed to resist the effects of earthquake

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1613.2.2 Site class definitions. Based on the site soil properties, the site shall be classified as Site Class A, B, C, D, E or F in accordance with Chapter 20 of ASCE 7.

Where the soil properties are not known in sufficient detail to determine the site class, Site Class D, subjected to the requirements of Section 1613.2.3, shall be used unless the building official or geotechnical data determines that Site Class E or F soils are present at the site.

Where site investigations that are performed in accordance with Chapter 20 of ASCE 7 reveal rock conditions consistent with Site Class B, but site-specific velocity measurements are not made, the site coefficients Fa and Fv shall be taken at unity (1.0).

1613.2.3 Site coefficients and adjusted maximum con- sidered earthquake spectral response acceleration parameters. The maximum considered earthquake spectral response acceleration for short periods, SMS, and at 1second period, SM1, adjusted for site class effects shall be determined by Equations 16-36 and 16-37, respectively:

SMS = FaSs (Equation 16-36)

SM1 = Fv S 1 (Equation 16-37)

but SMS shall not be taken less than SM 1 except when determining the seismic design category in accordance with Section 1613.2.5.

where: Fa = Site coefficient defined in Table 1613.2.3(1). Fv = Site coefficient defined in Table 1613.2.3(2). SS = The mapped spectral accelerations for short periods

as determined in Section 1613.2.1. S 1 = The mapped spectral accelerations for a 1-second

period as determined in Section 1613.2.1.

Where Site Class D is selected as the default site class per Section 1613.2.2, the value of Fa shall be not less than 1.2. Where the simplified design procedure of ASCE 7 Section 12.14 is used, the value of Fa shall be determined in accordance with ASCE 7 Section 12.14.8.1, and the values of Fv, SMS and SM 1 need not be determined. 1613.2.4 Design spectral response acceleration parame- ters. Five-percent damped design spectral response acceleration at short periods, SDS, and at 1-second period, SD1,

where: SMS = The maximum considered earthquake spectral

response accelerations for short period as determined in Section 1613.2.3. SM1 = The maximum considered earthquake spectral

response accelerations for 1-second period as determined in Section 1613.2.3.

1613.2.5 Determination of seismic design category. Structures classified as Risk Category I, II or III that are located where the mapped spectral response acceleration parameter at 1-second period, S 1, is greater than or equal to 0.75 shall be assigned to Seismic Design Category E. Structures classified as Risk Category IV that are located where the mapped spectral response acceleration parameter at 1second period, S 1, is greater than or equal to 0.75 shall be assigned to Seismic Design Category F. Other structures shall be assigned to a seismic design category based on their risk category and the design spectral response acceleration parameters, SDS and SD 1, determined in accordance with Sec tion 1613.2.4 or the site-specific procedures of ASCE 7. Each building and structure shall be assigned to the more severe seismic design category in accordance with Table 1613.2.5(1) or 1613.2.5(2), irrespective of the fundamental period of vibration of the structure, T .

Exception: [OSHPD 1R, 2 & 5] Structures not assigned to Seismic Design Category E or F above shall be assigned to Seismic Design Category D.

1613.2.5.1 Alternative seismic design category deter- mination. Where S1 is less than 0.75, the seismic design category is permitted to be determined from Table 1613.2.5(1) alone where all of the following apply:

In each of the two orthogonal directions, the approximate fundamental period of the structure, Ta, in each of the two orthogonal directions determined in accordance with Section 12.8.2.1 of

shall be determined from Equations 16-38 and 16-39, respectively:

SDS

SD1

2 = 3 ^- ^- ^SMS

2 = 3 ^- ^- ^SM1

(Equation 16-38)

(Equation 16-39)

TABLE 1613.2.3(1)

	VALUES OF SITE COEFFICIENT Fa a
SITE CLASS	MAPPED RISK TARGETED MAXIMUM CONSIDERED EARTHQUAKE (MCER) SPECTRAL RESPONSE ACCELERATION PARAMETER AT SHORT PERIOD	MAPPED RISK TARGETED MAXIMUM CONSIDERED EARTHQUAKE (MCER) SPECTRAL RESPONSE ACCELERATION PARAMETER AT SHORT PERIOD	MAPPED RISK TARGETED MAXIMUM CONSIDERED EARTHQUAKE (MCER) SPECTRAL RESPONSE ACCELERATION PARAMETER AT SHORT PERIOD	MAPPED RISK TARGETED MAXIMUM CONSIDERED EARTHQUAKE (MCER) SPECTRAL RESPONSE ACCELERATION PARAMETER AT SHORT PERIOD	MAPPED RISK TARGETED MAXIMUM CONSIDERED EARTHQUAKE (MCER) SPECTRAL RESPONSE ACCELERATION PARAMETER AT SHORT PERIOD	MAPPED RISK TARGETED MAXIMUM CONSIDERED EARTHQUAKE (MCER) SPECTRAL RESPONSE ACCELERATION PARAMETER AT SHORT PERIOD
SITE CLASS	Ss ≤ 0.25	Ss = 0.50	Ss = 0.75	Ss = 1.00	Ss = 1.25	Ss ≥ 1.5
A	0.8	0.8	0.8	0.8	0.8	0.8
B	0.9	0.9	0.9	0.9	0.9	0.9
C	1.3	1.3	1.2	1.2	1.2	1.2
D	1.6	1.4	1.2	1.1	1.0	1.0
E	2.4	1.7	1.3	Note b	Note b	Note b
F	Note b	Note b	Note b	Note b	Note b	Note b

a. Use straight-line interpolation for intermediate values of mapped spectral response acceleration at short period, Ss . b. Values shall be determined in accordance with Section 11.4.8 of ASCE 7.

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Exception: [OSHPD 1R, 2 & 5] Seismic design cat- egory shall be determined in accordance with exception to Section 1613.2.5.

1613.3 Ballasted photovoltaic panel systems.¶

Ballasted, roofmounted photovoltaic panel systems need not be rigidly attached to the roof or supporting structure. Ballasted non-penetrating systems shall be designed and installed only on roofs with slopes not more than one unit vertical in 12 units horizontal. Ballasted nonpenetrating systems shall be designed to resist sliding and uplift resulting from lateral and vertical forces as required by Section 1605, using a coefficient of friction determined by acceptable engineering principles. In structures assigned to Seismic Design Category C, D, E or F, ballasted nonpenetrating systems shall be designed to accommodate seismic displacement determined by nonlinear response-history or other approved analysis or shake-table testing, using input motions consistent with ASCE 7 lateral and vertical seismic forces for nonstructural components on roofs. [OSHPD 1R, 2 & 5] Ballasted photovoltaic panel systems shall be con- sidered as an alternative system.

ASCE 7, is less than 0.8 Ts determined in accordance with Section 11.8.6 of ASCE 7.

In each of the two orthogonal directions, the fundamental period of the structure used to calculate the story drift is less than Ts .
Equation 12.8-2 of ASCE 7 is used to determine the seismic response coefficient, Cs .
The diaphragms are rigid or are permitted to be idealized as rigid in accordance with Section 12.3.1 of ASCE 7 or, for diaphragms permitted to be idealized as flexible in accordance with Section 12.3.1 of ASCE 7, the distances between vertical elements of the seismic force-resisting system do not exceed 40 feet (12 192 mm).

Exception: [OSHPD 1R, 2 & 5] Seismic design cat- egory shall be determined in accordance with exception to Section 1613.2.5.

1613.2.5.2 Simplified design procedure. Where the alternate simplified design procedure of ASCE 7 is used, the seismic design category shall be determined in accordance with ASCE 7.

TABLE 1613.2.3(2)

	VALUES OF SITE COEFFICIENT FV a
SITE CLASS	MAPPED RISK TARGETED MAXIMUM CONSIDERED EARTHQUAKE (MCER) SPECTRAL RESPONSE ACCELERATION PARAMETER AT 1-SECOND PERIOD	MAPPED RISK TARGETED MAXIMUM CONSIDERED EARTHQUAKE (MCER) SPECTRAL RESPONSE ACCELERATION PARAMETER AT 1-SECOND PERIOD	MAPPED RISK TARGETED MAXIMUM CONSIDERED EARTHQUAKE (MCER) SPECTRAL RESPONSE ACCELERATION PARAMETER AT 1-SECOND PERIOD	MAPPED RISK TARGETED MAXIMUM CONSIDERED EARTHQUAKE (MCER) SPECTRAL RESPONSE ACCELERATION PARAMETER AT 1-SECOND PERIOD	MAPPED RISK TARGETED MAXIMUM CONSIDERED EARTHQUAKE (MCER) SPECTRAL RESPONSE ACCELERATION PARAMETER AT 1-SECOND PERIOD	MAPPED RISK TARGETED MAXIMUM CONSIDERED EARTHQUAKE (MCER) SPECTRAL RESPONSE ACCELERATION PARAMETER AT 1-SECOND PERIOD
SITE CLASS	_S_1 ≤ 0.1	_S_1 = 0.2	_S_1 = 0.3	_S_1 = 0.4	_S_1 = 0.5	_S_1 ≥ 0.6
A	0.8	0.8	0.8	0.8	0.8	0.8
B	0.8	0.8	0.8	0.8	0.8	0.8
C	1.5	1.5	1.5	1.5	1.5	1.4
D	2.4	2.2c	2.0c	1.9c	1.8c	1.7c
E	4.2	3.3c	2.8c	2.4c	2.2c	2.0c
F	Note b	Note b	Note b	Note b	Note b	Note b

a. Use straight-line interpolation for intermediate values of mapped spectral response acceleration at 1-second period, S 1. b. Values shall be determined in accordance with Section 11.4.8 of ASCE 7. c. See requirements for site-specific ground motions in Section 11.4.8 of ASCE 7.

TABLE 1613.2.5(1) SEISMIC DESIGN CATEGORY BASED ON SHORT-PERIOD (0.2 second) RESPONSE ACCELERATION

VALUE OF S DS	RISK CATEGORY
*VALUE OFSDS***	I or II	III	IV
_SDS _< 0.167g	A	A	A
0.167g≤ _SDS _< 0.33g	B	B	C
0.33g≤ _SDS _< 0.50g	C	C	D
0.50g≤ SDS	D	D	D

TABLE 1613.2.5(2) SEISMIC DESIGN CATEGORY BASED ON 1-SECOND PERIOD RESPONSE ACCELERATION

VALUE OF S D1	RISK CATEGORY
*VALUE OFSD1***	I or II	III	IV
_SD1 _< 0.067g	A	A	A
0.067g≤ _SD1 _< 0.133g	B	B	C
0.133g≤ SD1 < 0.20g	C	C	D
0.20g≤ SD1	D	D	D

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FIGURE 1613.2.1(1) RISK-TARGETED MAXIMUM CONSIDERED EARTHQUAKE (MCER) GROUND MOTION RESPONSE ACCELERATIONS FOR THE

CONTERMINOUS UNITED STATES OF 0.2-SECOND SPECTRAL RESPONSE ACCELERATION (5% OF CRITICAL DAMPING)

(continued)

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FIGURE 1613.2.1(2) RISK-TARGETED MAXIMUM CONSIDERED EARTHQUAKE (MCER) GROUND MOTION RESPONSE ACCELERATIONS FOR THE

CONTERMINOUS UNITED STATES OF 1-SECOND SPECTRAL RESPONSE ACCELERATION (5% OF CRITICAL DAMPING)

(continued)

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FIGURE 1613.2.1(2)—continued RISK-TARGETED MAXIMUM CONSIDERED EARTHQUAKE (MCER) GROUND MOTION RESPONSE ACCELERATIONS FOR THE

CONTERMINOUS UNITED STATES OF 1-SECOND SPECTRAL RESPONSE ACCELERATION (5% OF CRITICAL DAMPING)

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FIGURE 1613.2.1(3) RISK-TARGETED MAXIMUM CONSIDERED EARTHQUAKE (MCER) GROUND MOTION RESPONSE ACCELERATIONS

FOR HAWAII OF 0.2- AND 1-SECOND SPECTRAL RESPONSE ACCELERATION (5% OF CRITICAL DAMPING)

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FIGURE 1613.2.1(6) RISK-TARGETED MAXIMUM CONSIDERED EARTHQUAKE (MCER) GROUND MOTION RESPONSE ACCELERATIONS FOR PUERTO RICO AND THE UNITED STATES VIRGIN ISLANDS OF 0.2- AND 1-SECOND SPECTRAL RESPONSE ACCELERATION

(5% OF CRITICAL DAMPING)

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FIGURE 1613.2.1(7) RISK-TARGETED MAXIMUM CONSIDERED EARTHQUAKE (MCER) GROUND MOTION RESPONSE ACCELERATIONS FOR GUAM AND THE NORTHERN MARIANA ISLANDS OF 0.2- AND 1-SECOND SPECTRAL RESPONSE ACCELERATION

(5% OF CRITICAL DAMPING)

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strength of the connection of the floor or roof system to the column in each direction of beam or slab reinforcement passing through the column.

1616.2.2 Structural steel, open web steel joist or joist girder, or composite steel and concrete frame struc- tures. Frame structures constructed with a structural steel frame or a frame composed of open web steel joists, joist girders with or without other structural steel elements or a frame composed of composite steel or composite steel joists and reinforced concrete elements shall conform to the requirements of this section.

1616.2.2.1 Columns. Each column splice shall have the minimum design strength in tension to transfer the design dead and live load tributary to the column between the splice and the splice or base immediately below.

1616.2.2.2 Beams. End connections of all beams and girders shall have a minimum nominal axial tensile strength equal to the required vertical shear strength for allowable stress design (ASD) or two-thirds of the required shear strength for load and resistance factor design (LRFD) but not less than 10 kips (45 kN). For the purpose of this section, the shear force and the axial tensile force need not be considered to act simultaneously.

Exception: Where beams, girders, open web joist and joist girders support a concrete slab or concrete slab on metal deck that is attached to the beam or girder with not less than ³ /8-inch-diameter (9.5 mm) headed shear studs, at a spacing of not more than 12 inches (305 mm) on center, averaged over the length of the member, or other attachment having equivalent shear strength, and the slab contains continuous distributed reinforcement in each of two orthogonal directions with an area not less than 0.0015 times the concrete area, the nominal axial tension strength of the end connection shall be permitted to be taken as half the required vertical shear strength for ASD or one-third of the required shear strength for LRFD, but not less than 10 kips (45 kN).